This invention relates to apparatus for controlling a plurality of electric motors under variable load conditions.
Shuttle cars used in underground mines commonly have independently driven wheels, with pairs of wheels on each side of the vehicle being driven by their own electric motor. In certain situations, one motor may be loaded more heavily than the other for instance, when turning a corner, the motor for the innermost wheels is loaded more heavily than that for the outermost wheels. With conventional motor controllers, the loading of one motor may result in an over-voltage being applied to the other motor, which may be damaged by the over-voltage or the resulting over-speed. The controller may also attempt to increase the power supply to the more heavily loaded motor, which may damage that motor.